将虚拟项添加到DataGrid中的DropDownList [英] Adding dummy item to DropDownList in a DataGrid

问题描述

大家好，


我在DataGrid中有一个DropDownList，它是从

数据库中的记录填充的。


我想添加一个可能是字符串的值，例如Select a Company;对于

，如果您选择

第一项，则不会触发OnSelectedIndex事件的第一项。


有没有人知道一个简单的方法吗？


我使用以下代码来获取内部的下拉列表

a在数据网格内的单元格放置在里面我的PageLoad函数：


Dim list As DropDownList = New DropDownList（）

Dim cell As TableCell = CType（list.Parent，TableCell）

Dim item As DataGridItem = CType（cell.Parent，DataGridItem）


Dim ddlCo As DropDownList = CType（item.FindControl（" ddlCo"），DropDownList）


ddlCo .Items.Add（" Select a Company"）


我得到臭名昭着的对象引用未设置为实例

对象在昏暗的项目线上...


感谢任何回复...

glenn

Hi folks,

I have a DropDownList in a DataGrid that is populated from records in a
database.

I want to add a value that might be a string such as "Select a Company" for
the first item since an OnSelectedIndex event is not fired if you select the
first item.

Does anyone know of an easy way to do this?

I am using the following code to get at the the dropdownlist that is inside
a cell within the datagrid which is placed inside my PageLoad function:

Dim list As DropDownList = New DropDownList ( )
Dim cell As TableCell = CType(list.Parent, TableCell)
Dim item As DataGridItem = CType(cell.Parent, DataGridItem)

Dim ddlCo As DropDownList = CType(item.FindControl("ddlCo"), DropDownList)

ddlCo .Items.Add("Select a Company")

I am getting the infamous "object reference not set to an instance of an
object" on the Dim item line...

Appreciate any replies...
glenn

推荐答案

你的代码没有意义例如


Dim list As DropDownList = New DropDownList（）


声明并启动一个名为list的DropdownList控件，然后


Dim cell As TableCell = CType（list.Parent，TableCell）


声明一个TableCell对象并将其设置为作为TableCell对象的单元控件的父控件

的值。但是在这一点上列表

对象，没有父控制。


你究竟想做什么？

" ;格伦"写道：

You code makes no sense for example

Dim list As DropDownList = New DropDownList ( )

declares and initiates a DropdownList control called list, then

Dim cell As TableCell = CType(list.Parent, TableCell)

declares a TableCell object and sets it to the value the the parent control
of the cell control cast as a TableCell object. But at this point the list
object, has no parent control.

What are you actually trying to do?
"glenn" wrote:

大家好，

我在DataGrid中有一个DropDownList，它是从
数据库中的记录中填充的。

我想添加一个可能是字符串的值，例如Select a Company;对于
第一项，因为如果您选择
第一项，则不会触发OnSelectedIndex事件。

是否有人知道一种简单的方法来执行此操作？
<我正在使用以下代码来获取位于我的PageLoad函数内的datagrid中的单元格内的下拉列表：

Dim list As DropDownList = New DropDownList （）
Dim cell As TableCell = CType（list.Parent，TableCell）
Dim item As DataGridItem = CType（cell.Parent，DataGridItem）

Dim ddlCo As DropDownList = CType （item.FindControl（" ddlCo"），DropDownList）

ddlCo .Items.Add（" Select a Company"）

我得到了臭名昭着的对象引用未设置为
对象的实例昏暗的项目线...

感谢任何回复...
glenn

Hi folks,

I have a DropDownList in a DataGrid that is populated from records in a
database.

I want to add a value that might be a string such as "Select a Company" for
the first item since an OnSelectedIndex event is not fired if you select the
first item.

Does anyone know of an easy way to do this?

I am using the following code to get at the the dropdownlist that is inside
a cell within the datagrid which is placed inside my PageLoad function:

Dim list As DropDownList = New DropDownList ( )
Dim cell As TableCell = CType(list.Parent, TableCell)
Dim item As DataGridItem = CType(cell.Parent, DataGridItem)

Dim ddlCo As DropDownList = CType(item.FindControl("ddlCo"), DropDownList)

ddlCo .Items.Add("Select a Company")

I am getting the infamous "object reference not set to an instance of an
object" on the Dim item line...

Appreciate any replies...
glenn

我想在我的ddl中添加一个虚拟值，这样当我在ddl中选择第一个

实数值时，会触发一个OnSelectedIndex事件。价值

可能是例如选择公司。


我认为我提供的代码需要提供才能找到

控制在DataGrid中。如果ddl不在DataGrid中我可以

只需写下类似的东西：

Dim ddl as DropDownList = e.Item.Cells（2）.FindControl（" ddlCompany" ;）

但由于它在DataGrid中，我需要额外的代码。


HTH。如果您知道更简单的方法，请告诉我。

谢谢，

glenn


" clickon"写道：

I am looking to add a dummy value to my ddl so that when I select the first
real value in the ddl, an OnSelectedIndex event will be fired. The value
might be for example, "Select a Company".

The code I presented I believe needs to be provided in order to find a
control that is inside a DataGrid. If the ddl was not in a DataGrid I could
simply write something like:
Dim ddl as DropDownList = e.Item.Cells(2).FindControl("ddlCompany")
but since it is inside the DataGrid, I needed the additonal code.

HTH. If you know of an easier way, please let me know.
Thanks,
glenn

"clickon" wrote:

你的代码没有意义，例如

Dim list As DropDownList = New DropDownList（）

声明并启动一个DropdownList控件调用list，然后

Dim cell As TableCell = CType（list.Parent，TableCell）

声明一个TableCell对象并将其设置为父控件的值<将单元格控件转换为TableCell对象。但是在这一点上列表
对象，没有父控制。

你究竟想做什么？

" glenn"写道：

You code makes no sense for example

Dim list As DropDownList = New DropDownList ( )

declares and initiates a DropdownList control called list, then

Dim cell As TableCell = CType(list.Parent, TableCell)

declares a TableCell object and sets it to the value the the parent control
of the cell control cast as a TableCell object. But at this point the list
object, has no parent control.

What are you actually trying to do?
"glenn" wrote:

大家好，

我在DataGrid中有一个DropDownList，它是从
数据库中的记录中填充的。

我想添加一个可能是字符串的值，例如Select a Company;对于
第一项，因为如果您选择
第一项，则不会触发OnSelectedIndex事件。

是否有人知道一种简单的方法来执行此操作？
<我正在使用以下代码来获取位于我的PageLoad函数内的datagrid中的单元格内的下拉列表：

Dim list As DropDownList = New DropDownList （）
Dim cell As TableCell = CType（list.Parent，TableCell）
Dim item As DataGridItem = CType（cell.Parent，DataGridItem）

Dim ddlCo As DropDownList = CType （item.FindControl（" ddlCo"），DropDownList）

ddlCo .Items.Add（" Select a Company"）

我得到了臭名昭着的对象引用未设置为
对象的实例在昏暗的项目线上......

感谢任何回复...
glenn

Hi folks,

I have a DropDownList in a DataGrid that is populated from records in a
database.

I want to add a value that might be a string such as "Select a Company" for
the first item since an OnSelectedIndex event is not fired if you select the
first item.

Does anyone know of an easy way to do this?

I am using the following code to get at the the dropdownlist that is inside
a cell within the datagrid which is placed inside my PageLoad function:

Dim list As DropDownList = New DropDownList ( )
Dim cell As TableCell = CType(list.Parent, TableCell)
Dim item As DataGridItem = CType(cell.Parent, DataGridItem)

Dim ddlCo As DropDownList = CType(item.FindControl("ddlCo"), DropDownList)

ddlCo .Items.Add("Select a Company")

I am getting the infamous "object reference not set to an instance of an
object" on the Dim item line...

Appreciate any replies...
glenn

只需将其添加到您的SQL


SELECT添加公司

UNION

SELECT CompanyName from Companies


" glenn" < GL *** @ discussions.microsoft.com>在留言中写道

news：68 ********************************** @ microsof t.com ...

Just add it to your SQL

SELECT "add a company"
UNION
SELECT CompanyName from Companies

"glenn" <gl***@discussions.microsoft.com> wrote in message
news:68**********************************@microsof t.com...

我希望在我的ddl中添加一个虚拟值，这样当我在ddl中选择第一个
实际值时，将触发OnSelectedIndex事件。值
可能是例如选择公司。

我认为需要提供的代码是为了找到一个内部的控件。数据网格。如果ddl不在DataGrid中，我可以简单地写出如下内容：
Dim ddl as DropDownList = e.Item.Cells（2）.FindControl（" ddlCompany"）
但由于它在DataGrid中，我需要附加代码。

HTH。如果您知道更简单的方法，请告诉我。
谢谢，
glenn

clickon写道：

I am looking to add a dummy value to my ddl so that when I select the first
real value in the ddl, an OnSelectedIndex event will be fired. The value
might be for example, "Select a Company".

The code I presented I believe needs to be provided in order to find a
control that is inside a DataGrid. If the ddl was not in a DataGrid I
could
simply write something like:
Dim ddl as DropDownList = e.Item.Cells(2).FindControl("ddlCompany")
but since it is inside the DataGrid, I needed the additonal code.

HTH. If you know of an easier way, please let me know.
Thanks,
glenn

"clickon" wrote:

你的代码没有意义，例如

Dim list As DropDownList = New DropDownList（）

声明并启动一个DropdownList控件调用list，然后

Dim cell As TableCell = CType（list.Parent，TableCell）

声明一个TableCell对象，并将其设置为父控制单元格控件转换为TableCell对象。但此时
列表
对象，没有父控件。

你究竟想做什么？

" glenn"写道：

You code makes no sense for example

Dim list As DropDownList = New DropDownList ( )

declares and initiates a DropdownList control called list, then

Dim cell As TableCell = CType(list.Parent, TableCell)

declares a TableCell object and sets it to the value the the parent
control
of the cell control cast as a TableCell object. But at this point the
list
object, has no parent control.

What are you actually trying to do?
"glenn" wrote:

>嗨伙计们，
>
>我在DataGrid中有一个DropDownList，它是从
>中的记录填充的。数据库。
>
>我想添加一个可能是字符串的值，例如选择公司
>对于
>如果你没有触发OnSelectedIndex事件，那么第一项是
>选择
>第一项。
>
>有谁知道一个简单的方法吗？
>
>我使用以下代码来获取
>的下拉列表里面
>数据网格中的一个单元格放在我的PageLoad函数中：
>
> Dim list As DropDownList = New DropDownList（）
> Dim cell As TableCell = CType（list.Parent，TableCell）
> Dim item As DataGridItem = CType（cell.Parent，DataGridItem）
>
> Dim ddlCo As DropDownList = CType（item.FindControl（" ddlCo"），
> DropDownList）
>
> ddlCo .Items.Add（" Select a Company）
>
>我得到臭名昭着的对象引用未设置为
>的实例
>对象"在昏暗的项目行...
>
>感谢任何回复...
> glenn
>
>
>
>

> Hi folks,
>
> I have a DropDownList in a DataGrid that is populated from records in a
> database.
>
> I want to add a value that might be a string such as "Select a Company"
> for
> the first item since an OnSelectedIndex event is not fired if you
> select the
> first item.
>
> Does anyone know of an easy way to do this?
>
> I am using the following code to get at the the dropdownlist that is
> inside
> a cell within the datagrid which is placed inside my PageLoad function:
>
> Dim list As DropDownList = New DropDownList ( )
> Dim cell As TableCell = CType(list.Parent, TableCell)
> Dim item As DataGridItem = CType(cell.Parent, DataGridItem)
>
> Dim ddlCo As DropDownList = CType(item.FindControl("ddlCo"),
> DropDownList)
>
> ddlCo .Items.Add("Select a Company")
>
> I am getting the infamous "object reference not set to an instance of
> an
> object" on the Dim item line...
>
> Appreciate any replies...
> glenn
>
>
>
>

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